Motutangi farmer Sylvia Bryan said the law requiring archaeological assessments of land prior to sale is unfair, given that the owner has to pay the cost of a process over which they have no control and cannot avoid.
Heritage New Zealand said the process is important, while the cost is often modest in comparison with other costs associated with a change of land use.
Mrs Bryan said two attempts to sell part of her and her late husband Norm's farm had fallen through in two months because of the fear generated by "archaeological issues", although "there is no archaeological stuff except 100 years ago a farmer dug a ditch nearby and they want to dig up the whole area, just because they can with the present laws".
A neighbour, she said, had accrued a debt of around $300,000, "and rising fast", over a period of three months.
"Everybody is afraid," she added.
"The archaeologists have absolutely no controls or constraints on their work.
"They are a law unto themselves. We have no idea of their wage structures.
"They can charge whatever they want and bring in whatever tools and machinery they want with no thought of budget. We have no finite time or cost to work with where they are concerned.
"It is bad enough that we lose the use of the land we own, maybe permanently, but the biggest problem is that the owner has to bear the whole cost ... The law needs to be overhauled. If they want to dig etc, let them find the money from somewhere else.
"Why should the land owner have to bear the whole cost of something that has absolutely no value to him, now or later?" she said.
"This is rather urgent as it affects me right now. I am nearer 80 than 70, and want to move. I have no other way of getting the necessary funds. In short, the owner loses the land, gets no compensation, and has to pay whatever they ask with no constraints over them.
"A cross on an old map (before GPS) had them come up and check the spot, and even though we told them there was absolutely nothing, we had to pay the $380 for them to prove us correct before we could sell that block."
The previous owner of the Mapua avocado block, just south of Mrs Bryan's farm, had said his father had remembered a time when one had had to use a boat to get from Whaler's Rd to the pa on Motutangi Rd.
"The land in question was lake or swamp so no living was done on that land, and no archaeological survey is needed," she said.
"When Mapua was a dairy farm it gave one family a moderate living.
"Now, as an avocado block, it is paying over 20 fulltime wages, so 20 families get a living from the same land.
"While these archaeological investigations are holding up sales they are holding back the North big time.
"There is no accountability, no cap on time, and no cap on expenses that we can see."
Site has rich archaeological heritage
Heritage New Zealand's Northland manager, Bill Edwards, said the landscape referred to by Mrs Bryan had an extensive archaeological context including taro fields, drains and other Maori gardening systems. Although some had been damaged, they were still significant as they told how people lived there in the past.
There was also evidence of habitation in the form of a nearby pa site.
"One of the NZ Archaeological Association site records for this property is 10 pages long, an indicator of the rich archaeological heritage associated with this site," Mr Edwards said.
"Our advice to the land owner has been that if earthworks are to be carried out an archaeological assessment will need to be undertaken, so that Heritage New Zealand Pouhere Taonga is able to make an informed decision about whether an archaeological authority would be needed.
"The cost of an assessment would vary, depending on the scale of works planned, as it would for any other cost associated with re-purposing land on a large scale, and we always recommend that people get a number of quotes from different contractors to get the best price.
"The cost of compliance with an archaeological authority would be nothing like the figure of $300,000, as it relates to a neighbouring property. It should also be noted that we have had no complaints or correspondence from this particular property owner as regards archaeological costs."
Changing land use from dairying to large-scale avocado production carried its own costs, he added, including council consents, earthworks and irrigation and so on. Costs associated with archaeology would be part of overall expenditure, but would generally be modest compared with other costs.
"Given the archaeological significance of this area, it is important that information about these places is captured, as extensive earthworks destroy all archaeological sites," Mr Edwards said.
"The authority process also allows for the possibility of avoiding these sites altogether in some situations, while still enabling development to proceed."